The present invention relates to a single coil actuator for low and medium voltage applications, in particular to a single coil actuator based on a single coil electromagnet having improved features in terms of performances and construction. The single coil actuator of the invention is conveniently used in low and medium voltage apparatuses. For the purposes of the present application the term medium voltage is referred to applications in the range of between 1 and 50 kV and low voltage is referred to applications in the range below 1 kV.
Coil-based actuators are frequently used in medium and low voltage apparatuses, for instance in low or medium voltage circuit breakers, disconnectors or contactors, for a wide variety of applications. A typical use of coil-based actuators is to release or lock mechanical parts of spring-actuated circuit breaker, following an opening or closing command. Other typical uses are, e.g., locking magnet for truck, command locking, and similar.
Conventional coil-based actuators normally comprise an electronics that drives two windings which are selectively energized for moving the anchor associated thereto (“launch” operation) and for maintaining it into position (“hold” operation). The two windings are powered directly from the supply rail and switched using two MOSFETs: the first coil is switched on to launch the electromagnet and the second coil allows to keep the electromagnet into position.
Even if conventional coil-based actuators are widely and satisfactorily used, they have however a number of disadvantages.
A first problem derives from the high number of variants which are needed to cover all operational ranges. As an example, up to 7 electromagnet variants are needed to support all voltage and current (AC and DC) operational ranges. In turn, each electromagnet variant needs its own driving electronics. Such a high number of variations has a negative impacts on manufacturing and handling costs.
Another disadvantage derives from the coil manufacturing; in particular the “hold” winding requires an high number of turns with very low wire sections. This makes the coil expensive.
Another disadvantage derives from the possibility to interface the coil either with dedicated electronics or with electronics already on-board of the medium or low voltage apparatus in which the coil is installed. Normally, the electromagnet is connected to the electronic box using cables that need manual forming and soldering on the coil winding. This requires a further possible variant in the design of the coil, as well as the need of soldering operation of the connections.
It is therefore an aspect of the present invention to provide a coil-based actuator for medium or low voltage applications in which the above-mentioned drawbacks are avoided or at least reduced.
More in particular, it is an aspect of the present invention to provide a coil-based actuator for medium or low voltage applications having a simplified design, maintaining at the same time the performances and the reliability needed for the intended applications.
As a further aspect, the present invention is aimed at providing a coil-based actuator for medium or low voltage applications that can be easily adapted to a wide number of intended applications.
Still a further aspect of the present invention is to provide a coil-based actuator for medium or low voltage applications that can be easily interfaced with dedicated electronics or with electronics already on-board of the medium or low voltage apparatus in which the actuator is installed.
As a further aspect, the present invention is aimed at providing a coil-based actuator for medium or low voltage applications having a reduced number of mechanical parts.
Still another aspect of the present invention is to provide a coil-based actuator for medium or low voltage applications with reduced manufacturing and installation costs.